Applications of new methods of phosphorylation developed under Grant 5-R01-GM 20672 to the synthesis of deoxyribooligonucleotides and ribooligonucleotides by stepwise and by block condensations of nucleosides in solution and on insoluble polymer supports are proposed in this Grant Application. The reagents are pyrophosphate, phosphorochloridate and N-phosphoroimidazole derivative of the 2/oxo-4,5-dimethyl-l,3, 2-dioxaphospholyl group, a cyclic enediol phosphoryl derivative. The reagents converts two alcohols, RlOH and R2OH, into a phosphotriester, (RlO)(R2O)P(O)OCH(CH3)COCH3, without the need to introduce additional activating reagents; groups on the purine and pyrimidine bases need not be protected, and a minimum of protection of the sugar-OH groups is required. The triesters are easily converted into the phosphodiesters: (RlO)(R2O)P(O)OH, i.e., the nucleotides. The goal of the research is to make available in reasonably large amounts samples of deoxyribo- and ribooligonucleotides with the sequence of DNA's and of t-RNA's and also oligonucleotides derived from abnormal bases and sugars, for studies on mechanisms of transcription and translation of genetic information.